With the development of display technology, liquid crystal display (LCD) has become the most common display device. Among them, vertical alignment (VA) type liquid crystal display because of the wide viewing angle, high contrast advantages, has become the mainstream products on the market. At present, with the high demand for customers, the need to develop higher contrast LCD. High contrast means that the white screen brightness does not decline in the case, as far as possible to reduce the backlight has been open when the LCD black screen light leakage phenomenon, the light depends on the backlight design, but also depends on the LCD design and polarizer design. Among them, the pixel structure in the liquid crystal cell (Cell) has a significant impact on the light leakage, how to minimize the leakage of light to improve the contrast is the industry are seeking to solve the problem.